TextBox.BeforeTextChanging Event

Definition

Namespace:

Windows.UI.Xaml.Controls

Occurs synchronously when the text in the text box starts to change, but before the Text property is updated.

// Register
event_token BeforeTextChanging(TypedEventHandler<TextBox, TextBoxBeforeTextChangingEventArgs const&> const& handler) const;

// Revoke with event_token
void BeforeTextChanging(event_token const* cookie) const;

// Revoke with event_revoker
TextBox::BeforeTextChanging_revoker BeforeTextChanging(auto_revoke_t, TypedEventHandler<TextBox, TextBoxBeforeTextChangingEventArgs const&> const& handler) const;

public event TypedEventHandler<TextBox,TextBoxBeforeTextChangingEventArgs> BeforeTextChanging;

function onBeforeTextChanging(eventArgs) { /* Your code */ }
textBox.addEventListener("beforetextchanging", onBeforeTextChanging);
textBox.removeEventListener("beforetextchanging", onBeforeTextChanging);
- or -
textBox.onbeforetextchanging = onBeforeTextChanging;

Public Custom Event BeforeTextChanging As TypedEventHandler(Of TextBox, TextBoxBeforeTextChangingEventArgs) 

<TextBox BeforeTextChanging="eventhandler"/>

Event Type

TypedEventHandler<TextBox,TextBoxBeforeTextChangingEventArgs>

Windows requirements

Device family	Windows 10 Fall Creators Update (introduced in 10.0.16299.0)
API contract	Windows.Foundation.UniversalApiContract (introduced in v5.0)

See also

• TextBoxBeforeTextChangingEventArgs